I was wondering if changing R1 for a higher value (1K or something) would rectify the problem. I'm running it on 12V.

so it's coming a little short?

1st: running on 12V does notmake any difference.
2nd: which 4046 are you using?
3rd: R2 should be 390R NOT 100k as seen on the old BOM.
4th: you may want try to jumper R2 completely
5th: changing R1 shouldn't make any difference then (see 4th), since it is set up as a voltage divider._________________
cheers,
matthias
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im also getting range problems with mine, i have tried several ic's including mc14046, a national 4046, and the XNP HEF4046BP im getting a maximum of 3.8k hz (roughly) with a very slight variation between chips.
ive tried jumpering R2, doesnt seem to do much for the overall range

**edit** AHEM......i seem to have used a 100nf cap in C3....... sorry. and ty JovianPyx for pointing me in the right direction.

Sorry to dig up an old thread but I am having the exact same issue. I built my x4046 over the weekend and I could only get 11 semitones per volt tracking. I tried a TI and a national 4046 and got the same results. I used 1% resistors through out.

After lowering the 100k resitor to about 90k on the 1v/oct input I was able to get 1v/oct very easily over at least 5 octaves. Nice!

The other thing I found was I was able to trim the VCO offset without an oscilloscope by using a Multimeter set to DC voltage reading.

the TI part is known to not meet the criteria. the national, however, has been used in the past with success. you are the 1st one to have problems with the national. alas, i used the NXP part only, so i cannot say anything about the national...

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